Discussion regarding "MOST bus fault patterns" sticky thread

Edit:

Originally Posted by M.Wong

Please see sticky post at the top of the E65/66 section for the reference material.

LINK: http://bimmerfest.com/forums/showthread.php?t=300965

Discussion that followed is below.

bmwtech, thank you for the post! it is quite informative, and with my IT background, I understoof all of it quite easily... M. Wong I highly suggest this article be made a sticky, as it is very informative and I can see many people referring to this post for info....

Once again, the tech saves the day... someone needs to post that batman pic =)

Thanks for that write up, very interesting!

Thanks, I have problems with sound quality and it usually starts producing some strange noise after few minutes. I tried to "reset" it by unplugging the cable in the glove box, and sound was really better for about 10 minutes. Now it is back again. Will try to go to service.. ( sorry for simple English, I am from Europe )

Def should be sticky, M. wong can you please?

Thanks BMW_Tech for this very very helpful information.

Sustained noises in the CD Changer
---The MOST ring is permanently interrupted. Ring break or MOST bus diagnosis should be carried out.

Brief audio failures
A) When the failure occurs followed by a magazine check from the CD changer and the sound returns......
MOST likely cause :
Stationary vehicle: CD changer or Power Module disconnection.

My car always does something similar, but I am not too sure if it is the same case.
the CD changer is always disconnected and reloading itself when I first start the car in the morning when it's parked over night. But then it work perfectly fine if I dont leave the car off more than say around 8 hrs. In this case, is it the same cause? How should I address my problem with the dealer because last time we looked into this issue, they just cannot reproduce it in the short time. I hope you can give me some insight in pointing them the right direction. Thanks for your time and efforts.

Originally Posted by andynolife

Thanks BMW_Tech for this very very helpful information.


My car always does something similar, but I am not too sure if it is the same case.
the CD changer is always disconnected and reloading itself when I first start the car in the morning when it's parked over night. But then it work perfectly fine if I dont leave the car off more than say around 8 hrs. In this case, is it the same cause? How should I address my problem with the dealer because last time we looked into this issue, they just cannot reproduce it in the short time. I hope you can give me some insight in pointing them the right direction. Thanks for your time and efforts.

I suspect a parasitic draw. They just didn't want to deal with monitoring the draw. Ask to see the diagnosis report printout. See which bus MOST/CAN resets, see what module reports the MOST amount of reset or bus fault. Im pretty sure if you don't drive it for 2-3 days, you will get the battery warning or power module disconnection.

my car is doing the same as yours, i am working to get it fixed will post when i find somthing out


Rob.

My car stays in the garage for weeks at a time and I never have any of these problems (knock on wood)

Originally Posted by BMW_tech

I suspect a parasitic draw. They just didn't want to deal with monitoring the draw. Ask to see the diagnosis report printout. See which bus MOST/CAN resets, see what module reports the MOST amount of reset or bus fault. Im pretty sure if you don't drive it for 2-3 days, you will get the battery warning or power module disconnection.

Thanks for the input Tech
but I haven't driven the car for the past 7 days due to the crazy heavy snow, worst in 10 years for Vancouver. Yesterday i started the car and there was no warning or fault code what so ever, the car was in perfect condition. Again, the CD changer was disconnected and reloading itself as the car is unlocked as usual. Does it just have a mind of its own?
and I highly doubt I can reproduce the issue in the next dealership visit

Originally Posted by 745ByMySide

My car stays in the garage for weeks at a time and I never have any of these problems (knock on wood)

I tend to get less fault codes and stuff when my car sits for a couple days also. It just seems to have less problems when I let it sit for 2 days or so. Most of the time the steering wheel doesn't reset to the preset position, but when I let it sit for the weekend, it does.

Originally Posted by andynolife

Thanks for the input Tech
but I haven't driven the car for the past 7 days due to the crazy heavy snow, worst in 10 years for Vancouver. Yesterday i started the car and there was no warning or fault code what so ever, the car was in perfect condition. Again, the CD changer was disconnected and reloading itself as the car is unlocked as usual. Does it just have a mind of its own?
and I highly doubt I can reproduce the issue in the next dealership visit

That has to be easy to reproduce. Allow the vehicle to assume sleep mode. The next time you come in for service, speak to the shop foreman. Let him know that you will be coming around during your lunch break, if that's possible. Do not allow any dealer personnel to even move the car so ask the foreman to hang on to your key and repair order until you come around. I am guessing that since the CDC "resets", it does not remember the last CD and track when you turned off the ignition. There has to be a MOST bus fault, ask the foreman nicely to see what faults are stored. Let him know that your main concern is that you don't end up with a dead battery if there is a parasitic draw. You want to save yourself the "you don't drive the car often" speech that you've heard from other owners. And you do not want to wait until the other MOST bus modules become affected or show symptoms of BUS communication error or "reset". It's either CAN or MOST. But CAN will affect other audio sources such as PRESET/STORED stations. You do not want to experience a MOST haunting, screeching and speakers cutting in and out belongs in a haunted house.....NOT in your LOGIC seven. Look in while it sits in the garage every now and then, make sure that it remains asleep. Look at the "push to start" button and the seat switch and make sure that the backlighting isn't lit. Do not pull the outer door handle OR touch it if you have comfort access. You just want to make sure your baby is asleep. Remember that the TCU wakes up if you have BMW Assist. It may wake up the MOST since the CDC memory could not be retained. My apologies for the lengthy reply.

Wow How funny (well not funny) This morning im listening to my radio and my audio got really low, but i can still hear it. It sounded like only the woofers where on. I Turned off the car and turned back on, still sounded low. I waited 15 min with the car off then turned it back on the audio volume was back to normal. 3 minutes later audio got really low again.

Originally Posted by mcfalcons15

I tend to get less fault codes and stuff when my car sits for a couple days also. It just seems to have less problems when I let it sit for 2 days or so. Most of the time the steering wheel doesn't reset to the preset position, but when I let it sit for the weekend, it does.

Let me do some research. I remember reading something about this problem. I believe it's a SW issue. I have to dig through SIB's and PuMA cases. Bear with me. Check to see if your ODOMETER resets itself to zero or check to see if it remembers your KEY specific personalization. Use the other key for confirmation, you know what I am trying to get at. Also check and pay attention to your clock, make sure you don't lose minutes or any symptom like it. That's worse case scenario, it's when you shouldn't "let it slide" or ignore. That's how I "roll", never worry as long as Im around.

Originally Posted by andynolife

I highly doubt I can reproduce the issue in the next dealership visit

my dealer was able to replicate the problem when i took it in for the same problem... however, they kept doing band aid fixes and not checking up on their work, hoping i would just leave them alone or not care... so, i did what i had to... i video taped the phenomenon showing the car unlocking and the cdc shifting through all 6 discs, and starting from disc 1 track 1... i also showed in the video how nothing was installed in any external power element... i showed this to the service manager when i dropped it off and let them know that i wasn't playing around any more... thats when they replaced my power module and fixed it, after the 4th or 5th attempt!

Hi guys can anyone tell me were my Antenna module is! Ive done ring test and I'm informed that I have break between my Antenna Tuner and Voice Control System.
Thanks